按要求写句子。
1. This is an apple. (改为一般疑问句)
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2. They are playing football. (改为一般疑问句)
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3. I think it is a cat. (改为否定句)
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4. The cat is on the box. (对画线部分提问)
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5. Is she going to school today? (作否定回答)
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)。